物理化学学报

所属专题: 燃料电池

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PdNi/石墨烯气凝胶电催化甲酸氧化

包玉菲, 冯立纲   

  1. 扬州大学化学化工学院, 江苏 扬州 225002
  • 收稿日期:2020-08-13 修回日期:2020-09-08 录用日期:2020-09-08 发布日期:2020-09-14
  • 通讯作者: 冯立纲 E-mail:ligang.feng@yzu.edu.cn
  • 基金资助:
    国家自然科学基金(21972124,21603041)资助项目

Formic Acid Electro-oxidation Catalyzed by PdNi/Graphene Aerogel

Yufei Bao, Ligang Feng   

  1. School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, Jiangsu Province, China
  • Received:2020-08-13 Revised:2020-09-08 Accepted:2020-09-08 Published:2020-09-14
  • Supported by:
    The project was supported by the National Natural Science Foundation of China (21972124, 21603041).

摘要: 甲酸电氧化性能提升对发展直接甲酸燃料池至关重要。本文首次报道了采用简便的冷冻干燥/退火还原的方法将PdNi合金与三维石墨烯气凝胶进行了高效耦合并实现了对甲酸氧化反应的高效催化。利用X射线衍射、扫描电镜和透射电镜等仪器对催化剂的结构和形貌进行了表征,并对其催化甲酸氧化反应的性能进行了研究。PdNi以合金纳米粒子形式分散在三维石墨烯气凝胶(PdNi/GA)表面,PdNi/GA催化剂中Pd的XPS能谱有明显的位移,表明Pd,Ni和石墨烯气凝胶载体之间有较强的电子相互作用。电化学测试结果表明PdNi/GA催化剂具有很高的的甲酸电氧化性能,其峰值电流密度为136 mA·cm-2,分别是Pd/GA(68 mA·cm-2)和Pd/C(39.4 mA·cm-2)的2倍和3.45倍。在CO溶出伏安测试中,PdNi/GA催化剂的起始电位和峰电位分别是0.49和0.67 V,证明PdNi/GA催化剂具有优异的抗CO毒化能力。PdNi/GA良好的催化性能可以归因于石墨烯三维结构提供的优异的分散性及导电性和钯镍合金抗CO中毒能力的提升。

关键词: 甲酸氧化反应, 直接甲酸电池, 电催化剂, 钯基催化剂, 石墨烯气凝胶

Abstract: Direct formic acid fuel cells involve two significant half-reactions, namely formic acid electro-oxidation and oxygen reduction reaction, and the more sluggish and complex process for anode formic acid oxide also determine the whole fuel cells energy conversion efficiency. The most efficient catalysts rely on the noble metal of Pt and Pd based catalysts and compared with Pt catalysts, Pd catalyst is more appealing because of the low CO poisoning effect during the electro-oxidation of formic acid that mainly follows the direct pathway. The Pd alloy effect and support effect should be considered for the catalyst fabrication since the resulted structure and electronic modification could largely increase the catalytic performance. Graphene emerges out as novel support while the easy agglomeration and destruction of pure graphene do not guarantee promising merits. In this work, we demonstrated the formic acid oxidation ability boosting by facile coupling PdNi alloy and 3D graphene aerogel (PdNi/GA) via a freezing-drying/thermal annealing reduction approach. The PdNi alloy crystal structure was well confirmed by the X-ray diffractions technique and the alloy nanoparticles were successfully anchored on the 3D graphene aerogel surface. The electrochemical performance was evaluated for formic acid oxidation in the acid electrolyte. The PdNi/GA catalyst displayed a larger peak current density of 136 mA·cm-2, which was 2 and 3.45 times greater than Pd/GA (68 mA·cm-2) and Pd/C (39.4 mA·cm-2), respectively. The anti-CO poisoning ability was measured by CO stripping technique, and a low onset potential of 0.49 V was found on PdNi/GA catalyst, about 120 mV less than that of Pd/GA catalyst, indicating the oxophilic property of Ni to assist formic acid oxidation via the bi-functional mechanism. The oxidation peak potential of 0.67 V was observed on PdNi/GA, about 40 mV less than that of Pd/C catalyst, indicating the merits of 3D structure of graphene. Moreover, PdNi/GA catalyst had the highest mass activity of 1699 mA·mg-1 compared to Pd/GA (851 mA·mg-1) and Pd/C (537 mA·mg-1) catalysts. The specific activity of PdNi/GA was 2.6 mA·cm-2, which was 1.94 and 2.7 times of Pd/GA (1.34 mA·cm-2) and Pd/C (0.96 mA·cm-2) catalysts. The highly improved catalytic performance could be due to the combined alloy and support effect. The PdNi/GA was a promising catalyst for application in the direct formic acid fuel cells.

Key words: Formic acid oxidation reaction, Direct formic acid fuel cell, Electrocatalyst, Pd-base catalyst, Graphene aerogel

MSC2000: 

  • O646